package leetcode;

import javax.swing.tree.TreeNode;

/**
 * 二叉树的最近公共祖先
 */
public class Solution21 {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root == null || root == p || root ==q){
            return root;
        }

        TreeNode left = lowestCommonAncestor(root.left,p,q);
        TreeNode right = lowestCommonAncestor(root.right,p,q);

        //判读是否为空
        if(left == null && right == null){
            return null;
        }else if(left != null && right == null){
            return left;
        }else if(left == null && right != null){
            return right;
        }else{
            return root;
        }
    }
}
